Recently, greater importance is placed on environmental issues, and reduction of power consumption is demanded while information equipment is in the standby state in offices and homes. In order to reduce the power consumption during the standby state in the image processing apparatus such as an MFP (Multi Function Printer), the image processing apparatus is changed to a power saving standby mode to reduce the power consumption while being in the standby state, and the image processing apparatus returns to a normal operation mode when the image processing apparatus is used. Therefore, the power consumption is reduced as a whole.
In the conventional image processing apparatus, there is the well known apparatus, in which a power control unit for turning on a main power supply by connecting a USB interface cable connected to a personal computer in an energized state to a connector provided in a printing apparatus and, when a printing process is not performed for a predetermined time, the power control unit turns off the main power supply to shift to a reception standby state of a printer language by electric power supplied from the personal computer (Japanese Patent Application Laid-Open (JP-A) No. 2003-118204).
In the above conventional example, the main power supply is turned on to perform the printing at the time when the printer language is received. Therefore, the power consumption is reduced.
However, there is a problem that the shift to the power saving standby made is not assumed when the conventional image processing apparatus is used as the MFP, while there is no problem when the conventional image processing apparatus is used as SGP (Single Function Printer.
In the above conventional example, when a PC (Personal Computer) power supply is turned off, when a PC interrupts USB bus power, or when the USB (Universal Serial Bus) cable is unplugged, the main power supply is turned off, which results in the problem that startup cannot be performed by starting factors except for USB.